java日期,字符串用法 2019年3月28日
JAVA 

Scanner input = new Scanner(System.in);
System.out.println("请输入一串数字：");
String number = input.next();
StringBuffer strb = new StringBuffer(number);
System.out.println("请输入添加数字：");
String number2 = input.next();
strb.append(number2);
for(int i=3;i<(number+number2).length()+(number+number2).length()/3;i=i+4) {
  strb.insert(i, ",");
}
System.out.println(strb);


import java.text.SimpleDateFormat;
import java.util.Date;

public class Test {
  public static void main(String[] args) {
    Date date=new Date();
    SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    String now=format.format(date);
    System.out.println(now);  
    
}
}


import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Test {
  public static void main(String[] args) {
    Calendar cal=Calendar.getInstance();
    cal.set(2015,4-1,6);
    Date date=cal.getTime();
      SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");
      String now=format.format(date);
      System.out.println(now);
      System.out.println(now+"是2015年的第"+cal.get(Calendar.WEEK_OF_YEAR)+"周");
      System.out.println(now+"是2015年的第"+cal.get(Calendar.DAY_OF_YEAR)+"天");
    	  
}
}